From the earliest times people have established methods of evaluating the trustworthiness of an individual or organization (a natural or legal person). One common method for doing so is a formal organization that evaluates persons and vouches for their trustworthiness or provides objective information with which another person can perform its own evaluation. Examples of such organizations are Dun and Bradstreet, Consumers Union, The Better Business Bureau, the American Automobile Association and Michelin. People have also used informal means to establish the trustworthiness of a person by seeking recommendations from a friend, relative or co-worker.
Since the widespread adoption of the internet for communications and publishing, examples of formal evaluation organizations have become too numerous to count—an internet search on the term “hotel ratings” returns more than 50 million results. Commercial use of the internet by individuals has grown at a similar rate—a survey performed in 2005 shows that about one in six adult American internet users, or 25,000,000 people, have sold something on line. No single organization, much less a single person, can reliably evaluate more than a small fraction of these sellers by conventional means.